exxos's Atari, Amiga & retro forum

Daedalus wrote: 06 Jul 2022 15:29 You rang? :)
.....
But the biggest thing to consider is that the pins on the Checkmate A500 passthrough slot are mirrored. You'd need any adaptor board to take that into account, otherwise plugging an A2000 accelerator into the slot will connect pin 1-2, pin 2-1, pin 9-10, pin 10-9 and so on, which will likely let the magic smoke out of whatever gets 12V in through a clock line. As terriblefire said, this wasn't considered an issue at the time because A2000 accelerators were much too big to fit in the Checkmate case, but hey ho :)

Thanks for appearing with some solid info! :)

Upside down is a given for any cards using that slot, but it's also mirrored by design since there was a possibility of having that passthrough board permanently connected to the busboard. We went with the socket in the end, but the reversed pins remained. Pin 1 of the passthrough is at the bottom right of the slot, whereas pin 1 of the Zorro slot is at the top right. So I guess you could call it a death to all slot, yes :) It's why the warnings are on the board and in the manual to only use the provided adaptor board in that slot. I haven't heard of anyone trying to use an A2000 chip RAM expansion in the slot (they're generally pretty rare anyway since they're only really applicable to the original German A2000), but that probably wouldn't end well for the card...

@Daedalus :It took me a few goes to get the orientation right in my mind, after posting earlier! :lol:

But, yeah, I guess not many people attempting to do anything like this anyway, so not a big problem with flaming A500 side slots, eh? ;)

I guess we can just lay it to rest now.

Thanks again for chipping in with the details. :dualthumbup:

mrbombermillzy wrote: 06 Jul 2022 15:17

alexh wrote: 06 Jul 2022 15:03 FYI that was a typo, should have been MC68040FE33V. I can see why they are cheaper. The "V" means are 3.3V rather than "A" which is 5V. Must make them less desirable for classic computer users who presumably all need 5V versions.

Wouldn't a lower voltage translate to lower heat/more overclock potential though'?

Yes. But the FE (QFP) package is probably not as good with heat as the RC (PGA) package.

But they did make MC68040RC40V. I can only see them for sale direct from NXP / resellers for approx $250

alexh wrote: 06 Jul 2022 15:03 Nice

FYI that was a typo, should have been MC68040FE33V. I can see why they are cheaper. The "V" means are 3.3V rather than "A" which is 5V. Must make them less desirable for classic computer users who presumably all need 5V versions.

The CPU core voltage is flexible on the TF2040. Set it to whatever you need.

alexh wrote: 06 Jul 2022 16:41 Yes. But the FE (QFP) package is probably not as good with heat as the RC (PGA) package.

But they did make MC68040RC40V. I can only see them for sale direct from NXP / resellers for approx $250

You can use a 6-8 layer board for the adaptor and some heat paste under the CPU when you solder it down to dissipate some heat. You also have the possibility of building a cooling system onto the adaptor.

Stephen, probably somebody has asked but would you consider doing a 'long PCB' version of the card. The extra bit would just be for support (and I guess mounting an SSD or something (or a Hard Drive :D ) and wouldn't have any circuitry on it in my mind.

Kindest regards

Luke

Lukya wrote: 11 Jul 2022 12:09 Stephen, probably somebody has asked but would you consider doing a 'long PCB' version of the card. The extra bit would just be for support (and I guess mounting an SSD or something (or a Hard Drive :D ) and wouldn't have any circuitry on it in my mind.

Kindest regards

Luke

This goes against the general TF philosophy of make it as cheap as possible by default. I've also zero interest in having a second version of the card that ends up having different issues from the first one. Unlikely bit i'm not taking the chance...

Remember KEEP IT SIMPLE is the rule i go by. Thats why suggestions for extras are often knocked back.

But i could add mounting holes so something could be bolted there with a bracket I guess. thats as far as i'm prepared to go in terms of extras.

That would be great Stephen (the holes idea) - them someone can come up with a 3d printed frame etc.

Kindest regards

Luke

Lukya wrote: 11 Jul 2022 17:16 That would be great Stephen (the holes idea) - them someone can come up with a 3d printed frame etc.

Kindest regards

Luke

Keep in mind this is a rev0... which basically means pure prototype.

I know there are people out there who turn their noses up at Gayle emulation etc etc.

But the idea of these cards is that they can be manufactured and repair in perpetuity. I never claimed to make the bestest ever cards.

Ah man... I know y'all like this but when one of these pops in brand new i get a sinking feeling that I have a lot of work ahead of me.